I love how the watermelon looks like tomatoes.
1 cup watermelon cubes (to mimic a tomato look use a melon baller)
1 avocado, peeled and diced
¼ cup finely chopped red onion
4 tablespoons coarsely chopped fresh cilantro
2 tablespoons fresh lime juice
In a bowl, mix all the ingredients together gently. Chill and serve.
The whole melon balls were a bit big if you are eating this with tortilla chips. Half balls are better. The best and fastest is to slice the watermelon, cut around and remove the edge, then dice the fruit.